1. Field of the Invention
This invention is primarily directed to a fluid nozzle, and more particularly, to a tamper proof fluid nozzle incorporating a safety cut-off feature so that the nozzle becomes inoperative when the pressure of the fluid exiting the nozzle reaches a predetermined value.
2. Description of the Prior Art
U.S. Pat. No. 3,367,662 teaches a pressure shock absorber for gas-type welding systems wherein the gas pressure is extremely high. The self-equalizing shock absorbing valve of the shock absorber is normally biased open so that gas can flow thereby. Upon a surge of high pressure, the valve closes but automatically returns to open position after gas has bled through the valve from the high pressure side to the low pressure side. The valve is designed so that a restrictive passage is used to bleed fluid through the valve when the valve is closed. Also, the pressure shock absorber is designed to be removable. If it were desired to defeat the purpose of the pressure shock absorber, the shock absorber could be removed, thereby further allowing the shock absorbing valve to be removed which would defeat the function of the shock absorber.
The fluid nozzle described herein is designed to close and shut off the fluid exiting from the nozzle and remain in this closed and inoperative position until the fluid pressure exerted against the valve is reduced. The valve of the invention herein will not automatically reopen. The nozzle is designed to work at much lower pressures than the above-described pressure shock absorber and further the cut-off valve of the nozzle is designed so that the fluid basically passes through the valve rather than around the valve. Also, the nozzle of this invention is designed to be tamper proof in the cut-off valve cannot be removed from the nozzle after the nozzle has been assembled thereby overcoming the possibility that the safety cut-off feature of the nozzle may be defeated.
U.S. Pat. No. 2,245,271 teaches a safety cut-off valve designed to be inserted in a fluid pressure conduit between the source of supply and the end where used. Although the valve member in the safety cut-off valve is normally spring biased in an open position so that gas can pass through the valve, the valve is designed to close when there is a drop in pressure at the exit end of the valve. Once the safety cut-off valve has closed and become inoperative, several steps must be taken to restore the valve to an operative condition. These steps are turning off the pressure from the pressure source and venting the pressure source side of the valve by slightly unscrewing the coupling of the valve so that the biasing spring may overcome the pressure against the valve member and thereby restore the valve member to its original operational position. Also, the valve is made so that it can be disassembled which would allow the valve member to be removed if it were desired to defeat the purpose of the safety cut-off valve.
The nozzle of the invention described herein is designed to cut-off the fluid exiting from the nozzle when there is an increase in fluid pressure against the cut-off valve. When the cut-off valve closes the nozzle, thereby making it inoperative, there is no need to turn off the pressure from the fluid pressure source and vent the pressure source side of the nozzle by any unscrewing of the coupling of the valve. The nozzle will become operative again and allow fluid to pass therethrough merely by unplugging the vent holes, the plugging of which caused the increase in pressure and the inoperative condition in the first place, to reduce the pressure acting against the cut-off valve. As mentioned before, the nozzle is designed to be tamper proof so that the nozzle cannot be disassembled and the cut-off valve removed thereby overcoming the safety cut-off feature of the valve.
U.S. Pat. No. 2,929,399 teaches a fluid check valve to be used in a fluid pressure line between a pressure source and the end where the pressure is used. A ball is used as the valve member and is spring biased against the fluid which flows thereby. A drop in pressure on the use or exit side of the valve causes the valve member to close a port. The valve is designed to automatically leak air around the port so that, if pressure is again built up on the exit side of the valve, the spring will automatically return the ball to the operational position it was in before there was a decrease in pressure on the exit side of the valve. Again, the valve is made to be disassembled thereby allowing the ball valve member to be removed from the valve if it were desired to defeat the action of the check valve.
In the nozzle described herein, the cut-off valve reacts to an increase in pressure on the inlet side of the nozzle to force the valve to close the nozzle. Also, once the nozzle of this invention shuts off and becomes inoperative, it will remain so until the pressure exerted against the cut-off valve is decreased. It will not automatically return to its pre-cut-off position. Finally, the nozzle is assembled so that the cut-off valve cannot be removed from the interior of the nozzle to defeat the safety cut-off feature of the nozzle.